Can i do cardio and weight training together?

Yes: Yes of course you need both but do not over do it.

Sure: They often overlap. For example crossfit is a good combination. Best to do weights first and then cardio for best effect. If weight are done quickly you will get a cardio workout as well.

For sure: It is best for your health and fitness to do a combination of cardio and weights. However, i usually recommend doing cardio first to help you warm up your muscles. This can reduce injuries during weight training.